Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/16—Making hollow objects characterised by the use of the objects
  • B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
  • B21D51/44—Making closures, e.g. caps

Definitions

• the present invention relates to process for reforming the edge of a container opening cover and in particular to a method and apparatus for reforming the edge of a two piece or three piece shell before the shell is seamed to a container body to reduce scalloping or other irregularities in the shell perimeter.
• a container body has a side wall which is substantially cylindrical with at least one substantially circular rim defining an open end of the container body.
• a container end shell which is substantially disk- shaped (although it may have various recesses, scores, indicia and the like) has a perimeter substantially the same shape as the container opening rim.
• the container may be closed by seaming the angular region of the shell perimeter to the rim region of the container body such as by a double seaming operation, as known to those of skill in the art.
• a number of procedures often involved in providing or forming the shell result in a shell whose perimeter departs from perfect regularity (typically, departs from perfect circularity) such as when portions of the shell periphery are somewhat indented or scalloped, as compared to a perfect circular form.
• perfect regularity typically, departs from perfect circularity
• These departures of the shell periphery from ideal regularity contribute to container configurations in which the amount of material provided to achieve the seaming operations exceed the materials that are, at least theoretically, minimally required.
• annular region with a radial extent of X when, to achieve the desired seaming integrity, an annular region with a radial extent of X is needed, if the shell edge is scalloped inwardly by radial extent equal to Y, the shell must be provided with an annular seaming region having a nominal or intended radial extent of about X + Y (so that, even in portions of the annular region where scalloping occurs, the radial extent will be at least equal to the nominal or intended extent of X + Y, less the maximum scalloping defect of Y, to provide a guaranteed minimum radial extent of X, as desired).
• the shell In many container-forming procedures, it is desirable to provide seaming regions (or other regions) of the container end closure shell which has a degree of hardness, e.g. to assist in maintaining seam integrity, regardless of normal shocks or impacts on the container.
• the shell typically must have a diameter suited to the container body rim diameter, but which also has sufficient thickness to provide and maintain a reliable seam. Accordingly, it would be advantageous to provide a shell which provides for at least regions that are hardened, particularly in the annular seaming area. It would be advantageous to provide a process for forming shells that results in at least some increase in effective shell diameter, without thinning regions of the shell to the point that structural integrity may be compromised.
• the present invention involves subjecting the shell or shell blank to the application of a forming operation such as coining, spinning or die-forming at least in the periphery or seaming area of the shell, prior to the seaming operation.
• a forming operation such as coining, spinning or die-forming at least in the periphery or seaming area of the shell, prior to the seaming operation.
• the coining operation involves use of a die having a wall which can define the desired (typically, regular) shape of the shell periphery, so that coining may reform a shell from a shape which may have scalloped or otherwise irregular edges to a shape which has substantially regular, substantially unscalloped edges.
• the present invention allows the formation of containers having a seam size smaller than the seam size provided in correspondingly-shaped containers formed by previous procedures, substantially without sacrificing integrity or durability of the seam.
• the coining operation preferably provides an increase in the diameter of the shell (at at least some locations around the circumference) all having relatively minor effects on the thickness of the coined region.
• the coining achieves a degree of work-hardening of the coined area, which may help to offset the effects of any diminution of thickness caused by the coining operation.
• a non-precurled, non-curled shell is transferred to a reform station.
• This station contains a coin die and coin punch.
• the coin die has the desired round finished blank diameter machined into the die face.
• the die cavity has a round die wall which stops the outward flow of material during the coining process.
• the die wall produces the blank's final shape.
• the coining punch compresses the scalloped blank edge of the non-curled, non-precurled shell.
• Coining of the coined area causes the material to flow outward until it comes in contact with the die wall, forming the blanks outer diameter. This corrects the scalloped edge of the blanks and additionally work hardens the edge and increases the blank diameter.
• This configuration can also eliminate the need for (expensive) non-round cut edge tooling.
• FIG. 1 is a top plan view of an unreformed shell positioned in a coining die according to an embodiment of the present invention
• Fig. 2 is a cross sectional view of the shell and die taken along line 2-2 of Fig. 1, also showing a coining punch, according to an embodiment of the present invention
• Fig. 3 is an enlarged detail of region 3 of Fig. 2;
• Fig. 4 is a top plan view corresponding to the view of Fig. 1 but after a coining operation has been performed;
• Fig. 5 is a cross sectional view taken along line 5-5 of Fig. 4;
• Fig. 6 is a enlarged detail view of region 6 of Fig. 5;
• Fig. 7 is a flow chart showing selected steps in a shell forming and seaming operation according to previous procedures.
• Fig. 8 is a flow chart showing selected steps of a shell formation and seaming procedure, including coining according to embodiments of the present invention.
• a container end shell 112 is formed of a metal, such as an aluminum alloy.
• the container end shell 112 while roughly circular in shape, may have departures from strict circularity such as having one or more inwardly indented or scalloped regions 114a,b,c,d defining earring gaps.
• the departures from regularity can arise from a number of sources including imperfections in the original cutting or stamping of the planar or disk-shaped blank, shaping procedures such as stamping or other procedures for forming the annular recess 116 and/or the raised 118 periphery of the shell and may have contributions from the metallurgy of the shell and/or imperfections in tooling concentricity.
• a shell such as that depicted in Figs. 1 and 2 to have at least one and often plurality of scallops or earring gaps 114a-d.
• the radial extent 312 (Fig. 3) of the gap will, as shown, typically vary along the circumference of the shell. In a typical shell intended for use in forming a typical 12 ounce beverage container, the gap 312 is commonly no greater than about 0.0050 inches although there can be substantial variation in this value.
• the resultant variations in uncurled lip height lead to a double seam size which is greater than desired, thus increasing the material cost of the container.
• the shell 112 maybe reformed by coining some or, preferably all, peripheral areas of the shell.
• the shell 112 is positioned over or within the cavity 121 of a die 122.
• the die 122 has an annular surface 124 for receiving and supporting at least the annular periphery of the shell 112.
• Adjacent the outer edge of the support 124 is an upstanding wall region 126 of the die.
• the wall 126 defines the desired shape (such as circular) and diameter of the shell.
• a punch 212 is configured to cooperate with the die 122, to perform coining as described more thoroughly below.
• the punch 212 includes an outer cylindrical wall 214 with a shape and diameter to match (preferably with close tolerance) the shape and diameter of the die wall 126.
• the coining surface defines a generally annular flat region 216 extending radially inward a distance 612 (Fig. 6).
• a shell 112 is positioned in the cavity of the die 122 as depicted in Figs.
• the punch 212 is brought downward 218 with sufficient force to achieve coining as described below.
• the punch 212 causes plastic deformation of the metallic peripheral region of the shell.
• the coining process causes the coined area 412 (Fig. 4), to be reduced 616 in thickness, compared to the thickness 314 of the area prior to coining.
• the coining also results in shell material being displaced into the scalloped or gap regions 114a,b,c,d so that the coin material flows, generally in a net radially outward direction until it meets the die wall 126, as depicted in Fig. 6, thus achieving a shell periphery which has the regularity (and diameter) of the die wall 126.
• the total reduction in volume (the reduction in thickness) 616 times the area of the coined region 412 will not be substantially greater than the total volume of the pre-coining scalloped regions or gaps 114a,b,c,d.
• the coining will provide a reduction in thickness 616 of the periphery region of the shell which is small enough so as to not seriously affect the strength or integrity of the shell.
• the present invention preferably adds a process of coining to achieve edge reform 818, prior to the curling step 722 (and preferably prior to a pre- curl 720 end, and in the depicted embodiment, after other forming steps such as forming the annular recess 716.
• the present invention reduces or eliminates the effects of nonregularity or scalloping of blank or shell edges. Containers with smaller seam sizes can be achieved without compromising seam integrity or durability. Seam areas are provided which have been work-hardened and the increase in diameter arising form the coining operation results in savings of material. A number of variations and modifications of the invention can be used.
• the present invention for providing work hardening of the peripheral area of the shell without necessarily fully eliminating earring gaps.
• the present invention has been illustrated with examples of shells with circular ideal peripheries, the present invention could be used for shells (and containers) with noncircular shape such as ellipses, ovals, polygonal cross sections and the like.
• a radial extent 612 of a coining area has been provided, the present invention can be used with larger or smaller coining areas.
• the present invention has been illustrated by examples in which the coining operation is performed as a separate operation, it is possible to design processes in which the coining operation as described herein is performed simultaneously when one or more other operations such as a scoring operation, a recess or rib-forming operation, and the like.
• the depicted embodiment provides for a annular coining area which lies in a plane substantially parallel to the plane of the major web region of the shell, the coining area can be differently oriented.
• the inner wall 222 of the punch is conically shaped, (to assist in punch withdrawal) while the outer wall 214 is cylindrical, it is possible to provide a (preferably slight) bevel or angle to the outer wall (preferably with a corresponding angle to the die wall) to assist in punch withdrawal and/or guidance or alignment.
• the illustrated embodiments provide a punch coining surface 216 substantially parallel to the plane of the shell, it is possible to provide for the bottom surface of the punch (and thus of the resultant coining area) with a (preferably slight) inward or outward bevel.
• the disclosure herein has included a description of coining as a forming operation, other forming operations can also be used and can reduce or eliminate irregularities in the blank periphery, e.g. to permit smaller seams. Examples of other forming operations include spinning or die-forming. Those of skill in the art will understand how to use spinning or die-forming to reduce or eliminate irregularities, after understanding the present disclosure.
• the present invention in various embodiments, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, subcombinations, and subsets thereof. Those of skill in the art will understand how to make and use the present invention after understanding the present disclosure.
• the present invention in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, e.g. for improving performance, achieving ease and ⁇ or reducing cost of implementation.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Devices For Use In Laboratory Experiments (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Straightening Metal Sheet-Like Bodies (AREA)
• Making Paper Articles (AREA)

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• 2000
  • 2000-03-29 WO PCT/US2000/008382 patent/WO2001072446A1/en not_active Application Discontinuation
  • 2000-03-29 JP JP2001570394A patent/JP2003528729A/ja active Pending
  • 2000-03-29 BR BRPI0017173-5A patent/BR0017173B1/pt not_active IP Right Cessation
  • 2000-03-29 MX MXPA02009641A patent/MXPA02009641A/es unknown
  • 2000-03-29 AU AU2000240466A patent/AU2000240466A1/en not_active Abandoned
  • 2000-03-29 EP EP00919845A patent/EP1303366A1/en not_active Withdrawn

Non-Patent Citations (1)

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